Shock absorber



Nov. 26, 1929. A. L. BOEGEHOLD SHOCK ABSORBER File'd March 26, 1927 gmto o Patented Nov. 26, 12.2 2

siren stars insist EATET ALFRED L. BOEGEHOLD, 6F DETROZT, Ill/IICHIG-AN, ASSIGNOR 'IO GENERAL MOTORS RESEARCH CORPORATION, 0F DETROIT, Is'IlCHIG-AN, A CGRPGRATION OF DELAWARE Y SHOCK ABSORBER Application filed March 26, 1927. Serial No. 178,672.

This invention relates to shock absorbers or snubbers for vehicles, to cushion rebound after spring deflection and improve the riding qualities of the car.

The invention contemplates an improved type of shock absorber, in which a retracting spring or the like, resists the violent reaction or tendency of the vehicle body to bounce upward after the vehicle spring has been compressed. The past objection to this type of snubber, lies in the factthat when the vehicle spring is under maximum tension, the retracting or snubber spring is under minimum tension, and it does not reach its peak of resistance until the vehicle spring has returned to its normal position of minimum tension. Since the inital maximum expansive force of the vehicle spring on the rebound, acts against the minimum contractive force of the snubber spring, only a small resistance is at first offered thereto, and only as the reaction proceeds to completion does it meet with the increased resistance of the snubber spring. Thus the return of-the parts is not smooth and easy, and it is only during the latter portion of the rebound that there is present a cushioning effect of any consequence. T he relation of the two opposing forces being at such wide variance, it will be seen that the action of the snubber spring is not uniform or out the range of movement. I I a 1 To'meet the situation, it is proposed to eme'qual thruploy a rotating cam member in association with the retracting spring, which upon rotation presents a variable mechanical advan tage that is utilized to control the application of spring tension, to offer the proper degree of resistance thruout the relative movement of the frame and axle. The arrangement is such that the respective spring forces are brought into closer relation with each other, the retractive force of the snubber spring be ing always of slightly less value than the ex pansive force of the vehicle spring.

A preferred embodiment of the invention is illustrated in the accompanying drawing, wherein:

Figure 1 is a fragmentaryview showing a portion of a front axle supporting a chassis frame member, and the application of the present shock absorber. 1

Figure 2 is a vertical sectional View thru the casing for the operating parts, showing their relative positions.

Figure 3 is a View on line 33 of Figure 2.

Referring more particularly to the drawing, the reference character 1 indicates a channel shaped longitudinally extending side member of a vehicle chassis frame, which is flexibly supported by a multiple leaf, load bearing spring 2, upon the road axle 3. The load bearing spring may be of anv suitable character, that shown in the drawing being a semi-elliptical spring, pivotally connected at its ends to the frame member 1, by swinging shackle links as at 4.

Secured directly above the axle 3 to the frame member 1, by bolts/1 or the like, is a housing or casing 5, formed with integral bosses or lugs 6 and 7, projecting inwardly from the inner side wall thereof, which bosses 'may be apertured and interiorly screw threaded for engagement therein of studs or pins 8 and 9, which extend thru apertured bosses 10 and 11 on the outer wall of the casing.

The pin 8 in this instance, has mounted thereon a rotary drum or roller 12, and a helical coiled retracting spring 13 isshown surrounding the pin, having one extremity E.

turned radially inward as at 14, into engagement with an opening in the pin, while its other end 15, is. bent laterally and extends into the'hub of the rotary drum 12. The

other pin 9, serves as a fulcrum for the ellipr.

tical'cam or eccentric member 16, revolubly mounted thereon. One end of a flexible strap 17 is riveted or otherwise attached for wind ing upon the spring'retracted drum 12, and

the intermediate portion of the strap passes ing springs expanded to their full extent. Here the retracting spring 13 is under its maximum tension. Its force, however is exerted upon the short axis of the cam, the mechanical advantage of the cam favoring; the load supporting spring. Thebroken line position of the parts in this same figure,

illustrates the axle and frame members drawn close together, as when the load supporting spring is compressed by travel over uneven roadways. In this case, the spring 13 is retracted, after having rotated the drum 12 to take up slack in the strap, by winding the strap on the drum, and correspondingly turning the cam 16. The pull of the spring 13, whichis at minimum tension, acts directly on the long leverage or major axis of the cam, so that the effort of the retracting spring is multiplied thru the cam, to offset the maximum expansive tension of the supporting spring. The tension of the respective springs to be employed, is taken into account and the cam is so shaped or proportioned that the pull upward on the axle is at all times a few pounds less than the expansive tendency of the vehicle spring, whereby the restoration of the parts is smoothly accom plished and the body of the car is prevented from being thrown upward by the reaction or sudden rebound.

From the above description, it will be apparent that relative movement of the axle and frame permits an automatic adjustment of the rotary cam thruout the entire range of movement, giving a uniform interaction between opposing spring forces at all times.

While the device has'been more or less specifically described it is to be understood that it is not limited to the exact details shown, but that such modifications may be made as come within the scope of the appended claims. Having described my invention I claim: 1. In combination with a vehicle frame, an

axle and a load supporting spring interposed Y between the axle and frame, of a shock absorber comprising a spring el'ementcarried by the frame, a connection between the spring element and the axle through which the spring element exerts its tension in opposition to said load supporting spring, and

means associated with intermediate portion of said connection, adapted to afford avariable mechanical advantage to both springs, inversely with respect eachiotherto automatically maintain the effort of opposing springs inv substantially the same relation thruout the range of movement of the'axle and frame.

2. In combinatlonwith a vehicle frame, an axle and a load supporting spring interposed 7 between the axle and frame of a retractible spect to said spring element and a fiexiblestrap passing around and having an intermediate portion fixedly attached to the cam and having its opposite ends secured respectively to the spring element and axle, the relative movement of the axle and frame, thru said strap, retracting and expanding said spring element and rotating the cam to automatically vary the leverage afforded thereby inversely as'the value of the spring tension varies. I V

3. The combination with an expansible spring, a contractible spring, and a strap secured at opposite ends tothe respective springs, thru which said springs exert their influence in opposition to each other, of a rotary cam element having a connection with an intermediate portion of said strap,the cam. surface to: one side of said connection affording a bearing surface for a portion of the strap to provide a variable leverage effect on the action of one spring and the cam surface on the'othe-r side of said connection affording a bearing surface for another portion of the strap to provide a variable leverage effect on the action of the other spring.

4., The combination with an expansible spring, a contractible spring, and a strap secured at opposite ends to the respective springs, through which said springs exert their influence in opposition. to each other, of an eccentrically pivoted member over which the strap passes and to which an intermediate portion of the strap is connected adjacent the major axis of the eccentric member, the rotation of said member in one direction affording increased leverage in favor of the contractible spring as said spring contracts and'the rotation of said member in the opposite direction affording increased leverage in favor of the expansible spring as said springexpands. 7 5

i 5. The combination with an expansible spring, a contractible spring, and a strap se cured at opposite ends to the respective springs, through 'which said springs exert their influence in opposition to each other,

of i an eccentrically pivoted member over which the strap passes and to which aniintermediate portion of the strap is connected adjacent the major axis of the eccentric member, said strap being adapted to progressively bear upon'the receding surfaces of said memher on opposite sides of said major axis, as the member moves toward one or the other of its opposite limits, whereby themechanical advantage of said member favors'one or'the other of said springs depending upon the direction of rotation thereof.

6. A shock absorberfor vehicles having a chassis frame supported by a vehicle spring on an axle, including a rectractible element carried by the frame, a rotary cam member interposed between theaxle and said retractible element, a flexible strap fixed at opposite ends to the retractible element and axle respectively, and passing over and secured to the cam element adjacent the major axis thereof, whereby upon relative movement of the frame and axle, said cam element will be caused to rotate and afl'ect the opposing forces of said vehicle spring and retracting springby presenting a variable leverage efiect on both of said forces.

In testimony whereof I affix my signature.

ALFRED L. BOEGEHOLD. 

